The invention relates to devices for controlling dynamic vibration, and more particularly the invention relates to a fluid and elastomer vibration control device having a volume compensator and means for providing secondary compliance stiffness that are separate and discrete.
Fluid and elastomer apparatus, often referred to in the art as hydraulic mountings, isolators and dampers include a fluid which provides for a greater range of isolation and/or damping characteristics than may be achieved in mountings, isolators and dampers that incorporate an elastomer alone. The expanded isolation and/or damping that is achieved by a fluid and elastomer apparatus may be a result of an increase in damping or inertial forces.
Fluid and elastomer isolation apparatus may be either single acting where fluid is pumped in response to the dynamic movement of one or more isolator components in a first direction, or double acting where fluid is pumped in response to the dynamic displacement of one or more isolator components in first and second directions.
Prior art single acting isolation devices include a single means that compensates for both changes in fluid volume due to changes in isolator fluid temperature and/or pressure and also provides secondary compliance for changing the stiffness of the isolator for use in different applications. In prior art single acting isolators, the volume compensation means and means for changing the stiffness of the isolator is comprised of a single flexible diaphragm member.
In many instances such prior art single acting isolators provide effective volume compensation and secondary compliance. However, use of the diaphragm to achieve both volume compensation and secondary compliance has associated shortcomings. In operation, isolators undergo repetitive motion at high pressure, and over time the thin, flexible diaphragms wear out. Additionally, prior art isolators with a single element for producing the required volume compensation and changing the stiffness of the isolator cannot be tuned with the requisite precision or across a broad range of stiffness values. Isolator performance is improved by tuning the device to the suitable stiffness for a particular application. The isolators must be sufficiently flexible to rapidly compensate for static axial displacements in response to temperature buildup as well as dynamic movements, and to provide the appropriate fluid pressure. Stiff isolators that provide effective volume compensation are particularly difficult to provide using prior art systems and methods.
The foregoing illustrates limitations known to exist in present devices and methods. Thus, it is apparent that it would be advantageous to provide an alternative fluid and elastomer isolator that provides effective volume compensation and is tunable with precision and across a broad range of stiffness values. Accordingly, a suitable alternative is provided including features more fully disclosed hereinafter.
In one aspect of the present invention this is accomplished by providing a fluid and elastomer device including an inner member; and an elastomeric element flexibly interconnecting said inner member relative to said outer member. The fluid and elastomer device includes a compliance chamber; a primary working chamber; a compensator chamber; and a passageway interconnecting the primary working chamber and the compliance chambers. A secondary compliance member is located in the compliance chamber; and a volume compensator defines a portion of the compensator chamber. The volume compensator is located in a housing chamber and is separate from the compliance member.
In the fluid and elastomer device of the present invention the volume compensator includes a piston and diaphragm and the compensator is substantially unaffected by dynamic loading of the device, thereby increasing the useful life of the diaphragm. The fluid and elastomer device includes a restriction plate that defines a portion of the primary working chamber. The restriction plate is movable with the outer member.
The foregoing and other aspects will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawing figures.